Cisco CCNA Certification: Broadcasts, Unicasts, And Multicasts by Chris Bryant
When you begin your CCNA studies, you get hit with a lot of different networking terms right away that you might not be familiar with. What makes it a little more confusing is that a lot of these terms sound a lot alike. Here, we're going to discuss the differences between broadcasts,... (Keep in mind that switches will forward a broadcast, but routers do not.) In contrast to a broadcast, a unicast is a packet or frame with only one destination. ... As you climb the Cisco certification pyramid, you'll be introduced to creating multicast groups and controlling multicast traffic, but for...

CCNP Certification / BCMSN Exam Tutorial: QoS Service Types by Chris Bryant
To pass the CCNP exams, you’ve got to master Quality of Service, and the first step in doing so is knowing the differences between the different QoS types. Now this being Cisco, we can't just have one kind of QoS! We've got best-effort delivery, Integrated Services, and Differentiated Services. ... A packet can be considered "high priority" by one router and "normal priority" by the next. ... Of course, if you've got a lot of different dedicated paths being created that may or not be used very often, that's a lot of wasted bandwidth.

ARP, MAC, Poisoning, & WiFi by Brian Wilson
In this paper we will cover the basics on Address Resolution Protocol (ARP), Media Access Control Addresses (MAC), Wireless (WiFi), and layer 2 communications. I hope to explain how a “Man in the Middle Attack” works. The common name for this is ARP poisoning, MAC poisoning, or Spoofing. ... A network data frame, aka packet, includes checksum, source and destination address, and data. ... The data link layer handles the physical and logical connections to the packet's destination, using a network interface.

Penetration Testing on a Switched LAN by Brian Wilson
In this is article we will explore the presence of known vulnerabilities in switched LAN’s. I hope to open your eyes on some of the techniques & tools that can be freely downloaded and used to test your network. Let’s start out with some of the basics we see in most small to medium networks. ... If the device is a mail server it will normally report back to your telnet session with a service banner. ... Next step to test port 25 might be to telnet to the port and see if the reply is a banner. ... Microsoft Exchange server will report its SMTP name and the version of Exchange running on the...

Cisco CCNP / BCMSN Exam Tutorial: Multicasting And Reserved Addresses by Chris Bryant
Ever since you picked up your first CCNA book, you've heard about multicasting, gotten a fair idea of what it is, and you've memorized a couple of reserved multicasting addresses. Now as you prepare to pass the BCMSN exam and become a CCNP, you've got to take that knowledge to the next level and... 224.0.0.0 - 224.0.0.255 is reserved for network protocols only on a local network segment. ... Packets in this range will not be forwarded by routers, so these packets cannot leave the segment. ... That range contains a couple of other reserved address ranges.

OSI Layers Model by Kashif Raza
Introduction During the early years of our modern computer era, very few standards and protocols existed between various manufacturers. However, as time went on and computer technology continued to improve and become more widespread, it became apparent that standards would be necessary to... As a node receives data, each layer starting with the physical layer extracts the various portions of the packet and this process works its way up to the application layer. ... The data link layer consists of two sub layers; the logical link control (LLC) and the media access control (MAC), which...

CCNA 640-801 Certification Primer by Seema Kannan
The Cisco Certified Network Associate (CCNA) Certification is meant for career enhancement as well as gaining knowledge of the LAN/WAN technologies currently available for implementation. Hence, CCNA Certification can be obtained by IT professionals who have been a part of the industry for a... When switching between the simulator-based questions and the rest of the exam, the simulator engine may seem a little slow. ... Planning & Designing Design a simple LAN using Cisco Technology Design an IP addressing scheme to meet design requirements Select an appropriate routing protocol...

Cisco CCNA Certification Exam Case Study: Frame Relay, Pings, And Routing Protocols by Chris Bryant
Cisco CCNA certification training includes troubleshooting your own work and that of others. The best CCNA certification training you can do is indeed troubleshooting your own Cisco router and switch configurations - as I'm always telling my students, "I can guarantee that any error you make has... R1#debug ip rip RIP protocol debugging is on R1#clear ip route * 06:22:13: RIP: sending general request on Loopback0 to 224.0.0.9 06:22:13: RIP: sending general request on Serial0 to 224.0.0.9 06:22:13: RIP: ignored v2 packet from 1.1.1.1 (sourced from one of our addresses) 06:22:14: RIP:...

Design of Ideal Personal Firewall by David Matousek
Common concept This paragraph describes common concept of Windows personal firewalls. It is not necessary to implement the firewall in a similar way to have it secure . Common personal firewall is implemented as three or four separate components. Kernel driver The first part is kernel driver. ... Usually on the NDIS, TDI or both levels this driver checks every packet that comes in from the network or goes out to the network. ... The first function is a packet filter . ... Packet sniffers are waiting for the messages to be transferred using some network interface and they make copies...

Local Area Networks - Computer Networking by Michael Cooper
Local Area Networks also called LANs have been a major player in industrialization of computers. In the past 20 or so years the worlds industry has be invaded with new computer technology. It has made such an impact on the way we do business that it has become essential with an ever-growing need... A computer that receives the token is given permission to send a packet of information or, if the computer has no packet to send, it passed the token to the next computer.”(Local Area Network Microsoft 2000) I know that it is complicated to understand, but for the actual user the software takes...